Ion exchange materials

ABSTRACT

A method of preparing an ion-conducting material, for example membrane, having reduced sensitivity to water includes a step of treating an ion-conducting polymeric material (especially a sulphonated polyaryletherketone and/or sulphone) which has at least some crystallinity or which is crystallizable with a means to increase its crystallinity. The ion-conducting material prepared may be used in a Membrane Electrode Assembly of a fuel cell.

This invention relates to an ion-exchange materials (e.g. polymerelectrolyte membranes) and particularly, although not exclusively,relates to a method of preparing an ion-exchange membrane and such amembrane per se.

BACKGROUND OF THE INVENTION

One type of polymer electrolyte membrane fuel cell (PEMFC), shownschematically in FIG. 1 of the accompanying diagrammatic drawings, maycomprise a thin sheet 2 of a hydrogen-ion conducting Polymer ElectrolyteMembrane (PEM) sandwiched on both sides by a layer 4 of platinumcatalyst and an electrode 6. The layers 2, 4, 6 make up a MembraneElectrode Assembly (MEA) of less than 1 mm thickness.

In a PEMFC, hydrogen is introduced at the anode (fuel electrode) whichresults in the following electrochemical reaction:Pt-Anode (Fuel Electrode) 2H₂→4H⁺+4e⁻

The hydrogen ions migrate through the conducting PEM to the cathode.Simultaneously, an oxidant is introduced at the cathode (oxidantelectrode) where the following electrochemical reaction takes place:Pt-Cathode (Oxidant Electrode) O₂+4H⁺+4e⁻→2H₂O

Thus, electrons and protons are consumed to produce water and heat.Connecting the two electrodes through an external circuit causes anelectrical current to flow in the circuit and withdraw electrical powerfrom the cell.

Preferred ion-conducting polymeric materials for use as components ofpolymer electrolyte membranes in fuel cells have high conductivity (lowEW, or high ion-exchange capacities), low water uptake, robustness andsolubility in solvents which can be used to cast the membranes. However,some of the aforementioned requirements compete with one another. Forexample, steps taken to increase solubility of the materials in castingsolvents may, disadvantageously, increase the water uptake of thematerials; and steps taken to increase the conductivity of the materialswill tend also to increase water absorption leading to premature failureof the materials when used in fuel cells.

SUMMARY OF THE INVENTION

It is an object of the present invention to address problems associatedwith the provision of polymer electrolyte membranes.

According to a first aspect of the invention, there is provided a methodof preparing an ion-conducting membrane suitably having reducedsensitivity to water, the method including the step of treating a firstion-conducting polymeric material which has at least some crystallinityor which is crystallisable with a means to increase its crystallinity(hereinafter “crystallinity increasing means”), wherein said firstion-conducting polymeric material so treated (hereinafter “said treatedion-conducting material”) is a component of said ion-conductingmembrane.

Unless otherwise stated in this specification, a phenyl moiety may have1,4- or 1,3-, especially 1,4-, linkages to moieties to which it isbonded.

The existence and/or extent of crystallinity in a polymer is preferablymeasured by wide angle X-ray diffraction (also referred to as Wide AngleX-ray Scattering or WAXS), for example as described by Blundell andOsborn (Polymer 24, 953, 1983). Alternatively, Differential ScanningCalorimetry (DSC) could be used to assess crystallinity. The level ofcrystallinity in said first ion-conducting polymeric material may be 0%(e.g. where the material is crystallisable); or the level ofcrystallinity may be at least 1%, suitably at least 5%, is preferably atleast 10%, more preferably at least 15% and, especially, at least 20%weight fraction, suitably when measured as described by Blundell andOsborn. The level of crystallinity in said first polymeric material maybe less than 20%, preferably less than 15%, more preferably less than10%, especially less than 5%.

The level of crystallinity in said treated ion-conducting material,suitably measured as described above, may be at least 1% greater thanthe level of crystallinity in said first polymeric material. The levelof crystallinity may be 5% or greater. Suitably, the level ofcrystallinity is at least 10% greater, preferably at least 15% greater,more preferably at least 20% greater, especially at least 25% greater.

Said crystallinity increasing means may comprise heating said firstion-conducting polymeric material, suitably when in a substantially drystate. Preferably, said first polymeric material is heated at atemperature greater than its Tg, suitably under an inert, e.g. anitrogen, atmosphere, for at least 0.5 minutes and less than 30 minutes.Alternatively and/or additionally, said crystallinity increasing meansmay comprise treatment of said first ion-conducting polymeric materialwith a crystallinity increasing solvent. Preferred such solvents arepolar aprotic solvents and may include acetone, dimethyacetamide (DMA),dimethylformamide (DMF), tetrahydrofuran (THF) and dichloromethane.After use of a crystallinity increasing solvent, especially acetone,dichloromethane or tetrahydrofuran, there is preferably a further stepwhich involves removal of the solvent, for example by evaporation.

The sensitivity (or water uptake) of the first ion-conducting polymericmaterial may be assessed as described in the examples hereinafter. Thedifference between the sensitivity of the material to water before andafter treatment may be at least 5%, suitably at least 10%, preferably atleast 20%, more preferably at least 40%, especially at least 60%. Insome cases, it may be at least 80%

As described above, it is a requirement of said first ion-conductingpolymeric material that it has at least some crystallinity or iscrystallisable. The material may be made up of a number of repeat units,some of which may be crystallisable or have some crystallinity and someof which will be amorphous. For example, repeat units provided withion-exchange sites, for example sulphonate groups, will tend to beamorphous, as will repeat units which include bulky groups or —SO₂—.Repeat units which are crystalline or crystallisable suitably includemoieties which can be exchanged with ether units in a polyetherketonecrystal lattice. Ketone units and/or —S— units may be exchanged and may,therefore, be components of crystalline or crystallisable units.

Thus, said first ion-conducting polymer preferably includes a repeatunit which suitably includes aromatic group containing moieties linkedby —CO— and/or —Q— groups, where Q represents —O— or —S—, but does notinclude —SO₂— and/or any groups whose shape and/or conformation is/areincompatible with the crystalline conformation adopted bypolyetherketone units.

A preferred first ion-conducting polymeric material (also referred toherein as “first material”) is one having a moiety of formula

and/or a moiety of formula

and/or a moiety of formula

wherein at least some of the units I, II and/or III are funtionalized toprovide ion-exchange sites; wherein the phenyl moieties in units I, II,and III are independently optionally substituted and optionallycross-linked; wherein said material is crystallisable or crystalline;and wherein m, r, s, t, v, w and z independently represent zero or apositive integer, E and E′ independently represent an oxygen or asulphur atom or a direct link, G represents an oxygen or sulphur atom, adirect link or a —O—Ph—O— moiety where Ph represents a phenyl group andAr is selected from one of the following moieties (i)* or (i) to (x)which is bonded via one or more of its phenyl moieties to adjacentmoieties

In (i)*, the middle phenyl may be 1,4- or 1,3-substituted.

Suitably, to provide said ion exchange sites, said polymeric material issulphonated, phosphorylated, carboxylated, quaternary-aminoalkylated orchloromethylated, and optionally further modified to yield —CH₂PO₃H₂,—CH₂NR₃ ²⁰⁺ where R²⁰ is an alkyl, or —CH₂NAr₃ ^(x+) where Ar^(x) is anaromatic (arene), to provide a cation or anion exchange membrane.Further still, the aromatic moiety may contain a hydroxyl group whichcan be readily elaborated by existing methods to generate —OSO₃H and—OPO₃H₂ cationic exchange sites on the polymer. Ion exchange sites ofthe type stated may be provided as described in WO95/08581.

Preferably, said first material is sulphonated. Preferably, the onlyion-exchange sites of said first material are sites which aresulphonated.

References to sulphonation include a reference to substitution with agroup —SO₃M wherein M stands for one or more elements selected with dueconsideration to ionic valencies from the following group: H, NR₄ ^(y+),in which R^(y) stands for H, C₁–C₄ alkyl, or an alkali or alkaline earthmetal or a metal of sub-group 8, preferably H, NR₄ ⁺, Na, K, Ca, Mg, Fe,and Pt. Preferably M represents H. Sulphonation of the type stated maybe provided as described in WO96/29360.

Unless otherwise stated in this specification, a phenyl moiety may have1,4- or 1,3-, especially 1,4-, linkages to moieties to which it isbonded.

Said first material may include more than one different type of repeatunit of formula I; more than one different type of repeat unit offormula II; and more than one different type of repeat unit of formulaIII.

Said moieties I, II and III are suitably repeat units. In the polymer,units I, II and/or III are suitably bonded to one another—that is, withno other atoms or groups being bonded between units I, II, and III.

Where the phenyl moieties in units I, II or III are optionallysubstituted, they may be optionally substituted by one or more halogen,especially fluorine and chlorine, atoms or alkyl, cycloalkyl or phenylgroups. Preferred alkyl groups are C₁₋₁₀, especially C₁₋₄, alkyl groups.Preferred cycloalkyl groups include cyclohexyl and multicyclic groups,for example adamantyl. In some cases, the optional substituents may beused in the cross-linking of the polymer. For example, hydrocarbonoptional substituents may be functionalised, for example sulphonated, toallow a cross-linking reaction to take place. Preferably, said phenylmoieties are unsubstituted.

Another group of optional substituents of the phenyl moieties in unitsI, II or III include alkyls, halogens, C_(y)F_(2y+1) where y is aninteger greater than zero, O—R^(q) (where R^(q) is selected from thegroup consisting of alkyls, perfluoralkyls and aryls), CF═CF₂, CN, NO₂and OH. Trifluormethylated phenyl moieties may be preferred in somecircumstances.

Where said first material is cross-linked, it is suitably cross-linkedso as to improve its properties as a polymer electrolyte membrane, forexample to reduce its swellability in water. Any suitable means may beused to effect cross-linking. For example, where E represents a sulphuratom, cross-linking between polymer chains may be effected via sulphuratoms on respective chains. Alternatively, said polymer may becross-linked via sulphonamide bridges as described in U.S. Pat. No.5,561,202. A further alternative is to effect cross-linking as describedin EP-A-0008895.

However, for first materials according to the inventions describedherein which are crystalline there may be no need to effectcross-linking to produce a material which can be used as a polymerelectrolyte membrane. Such polymers may be easier to prepare thancross-linked polymers. Preferably, said first material is not optionallycross-linked as described.

Where w and/or z is/are greater than zero, the respective phenylenemoieties may independently have 1,4- or 1,3-linkages to the othermoieties in the repeat units of formulae II and/or III. Preferably, saidphenylene moieties have 1,4-linkages.

Preferably, the polymeric chain of the first material does not include a—S— moiety. Preferably, G represents a direct link.

Suitably, “a” represents the mole % of units of formula I in said firstmaterial, suitably wherein each unit I is the same; “b” represents themole % of units of formula II in said material, suitably wherein eachunit II is the same; and “c” represents the mole % of units of formulaIII in said material, suitably wherein each unit III is the same.Preferably, is in the range 45–100, more preferably in the range 45–55,especially in the range 48–52. Preferably, the sum of b and c is in therange 0–55, more preferably in the range 45–55, especially in the range48–52. Preferably, the ratio of a to the sum of b and c is in the range0.9 to 1.1 and, more preferably, is about 1. Suitably, the sum of a, band c is at least 90, preferably at least 95, more preferably at least99, especially about 100. Preferably, said first material consistsessentially of moieties I, II and/or III.

Said first material may be a homopolymer having a repeat unit of generalformula

or a homopolymer having a repeat unit of general formula

or a random or block copolymer of at least two different units of IVand/or V

wherein A, B, C and D independently represent 0 or 1 and E, E′, G, Ar,m, r, s, t, v, w and z are as described in any statement herein.

As an alternative to a polymer comprising units IV and/or V discussedabove, said first material may, be a homopolymer having a repeat unit ofgeneral formula

or a homopolymer having a repeat unit of general formula

or a random or block copolymer of at least two different units of IV*and/or V*, wherein A, B, C, and D independently represent 0 or 1 and E,E′, G, Ar, m, r, s, t, v, w and z are as described in any statementherein.

Preferably, m is in the range 0–3, more preferably 0–2, especially 0–1.Preferably, r is in the range 0–3, more preferably 0–2, especially 0–1.Preferably t is in the range 0–3, more preferably 0–2, especially 0–1.Preferably, s is 0 or 1. Preferably v is 0 or 1. Preferably, w is 0or 1. Preferably z is 0 or 1.

Preferably Ar is selected from the following moieties (xi)* and xi) to(xxi):

In (xi)*, the middle phenyl may be 1,4- or 1,3-substituted.

Preferably, (xv) is selected from a 1,2-, 1,3-, or a 1,5-moiety; (xvi)is selected from a 1,6-, 2,3-, 2,6- or a 2,7-moiety; and (xvii) isselected from a 1,2-, 1,4-, 1,5-, 1,8- or a 2,6-moiety.

One preferred class of first materials may include at least some ketonemoieties in the polymeric chain. In such a preferred class, the polymerpreferably does not only include —O— and —SO₂— moieties between aryl (orother unsaturated) moieties in the polymeric chain. Thus, in this case,suitably, a polymer of the first aspect does not consist only ofmoieties of formula III, but also includes moieties of formula I and/orII.

One preferred class of first materials does not include any moieties offormula III, but suitably only includes moieties of formulae I and/orII. Where said polymer is a homopolymer or random or block copolymer asdescribed, said homopolymer or copolymer suitably includes a repeat unitof general formula IV. Such a polymer may, in some embodiments, notinclude any repeat unit of general formula V.

Suitable moieties Ar are moieties (i)*, (i), (ii), (iv) and (v) and, ofthese, moieties (i)*, (i), (ii) and (iv) are preferred. Preferredmoieties Ar are moieties (xi)*, (xi), (xii), (xiv), (xv) and (xvi) and,of these, moieties (xi)*, (xi), (xii) and (xiv) are especiallypreferred. Another preferred moiety is moiety (v), especially, moiety(xvi). In relation, in particular to the alternative first materialscomprising units IV* and/or V*, preferred Ar moieties are (v) and,especially, (xvi).

Preferred first materials include an electron-rich, relativelynon-deactivated, easily sulphonatable unit, for example amulti-phenylene moiety or a fused-rings aromatic moiety, such asnaphthalene. Such an easy to sulphonate unit may be sulphonated underrelatively mild conditions to introduce two sulphonate groups per unit.Thus, preferred polymers may have at least 10π electrons in adelocalized aromatic moiety. The number of π electrons may be 12 orless. Preferred polymers include a biphenylene moiety. Other preferredpolymers include a naphthalene moiety.

Preferred polymers include said electron rich, non-deactivated, easilysulphonatable unit bonded to two oxygen atoms. Especially preferredpolymers include a —O-biphenylene-O— moiety. Other especially preferredpolymers is include a —O-naphthalene-O— moiety.

Preferred first materials include a first type of moiety which isrelatively difficult to sulphonate and a second type of moiety which isrelatively easy to sulphonate. For example, said second moiety may besulphonatable using the relatively mild method described in Example 2hereinafter, whereas the first moiety may be substantiallynon-sulphonatable in such a method. The use of the method of Example 2may be advantageous over currently used methods which use oleum. Apreferred second said moiety includes a moiety —Ph_(n)— wherein n is aninteger of at least 2. Said moiety is preferably bound to at least oneether oxygen. Especially preferred is the case wherein said moiety is—O—Ph_(n)—O— where said ether groups are para to the Ph—Ph bond.

Preferred first materials are copolymers comprising, preferablyconsisting essentially of, a first repeat unit which is selected fromthe following:

(a) a unit of formula IV wherein E and E′ represent oxygen atoms, Grepresents a direct link, Ar represents a moiety of structure (iv), mand s represent zero, w represents 1 and A and B represent 1;

(b) a unit of formula IV wherein E represents an oxygen atom, E′represents a direct link, Ar represents a moiety of structure (i), mrepresents zero, A represents 1, B represents zero;

(c) a unit of formula V wherein E and E′ represent oxygen atoms, Grepresents a direct link, Ar represents a moiety of structure (iv), mand v represent zero, z represents 1 and C and D represent 1;

(d) a unit of formula V wherein E represents an oxygen atom, E′represents a direct link, Ar represents a moiety of structure (ii), mrepresents 0, C represents 1, D represents 0; or

(e) a unit of formula V wherein E and E′ represents an oxygen atom, Arrepresents a structure (i), m represents 0, C represents 1, Z represents1, G represents a direct link, v represents 0 and D represents 1;

Other preferred first repeat units include:

(aa) a unit of formula IV wherein E represents an oxygen atom E′represents a direct link, Ar represents a structure (i)*, m represents0, A represents 1, B represents 0;

(bb) a unit of formula IV wherein E and E′ represent oxygen atoms, Arrepresents a structure (iv), m and w represent 0, G represents a directlink, s and r represent 1, A and B represent 1;

(cc) a unit of formula IV wherein E and E′ represent oxygen atoms, Arrepresents a structure (i), m and w represent 0, G represents a directlink, s and r represent 1, A and B represent 1;

and a second repeat unit which is selected from the following:

(f) a unit of formula IV wherein E and E′ represent oxygen atoms, Grepresents a direct link, Ar represents a moiety of structure (iv), mrepresents 1, w represents 1, s represents zero, A and B represent 1;

(g) a unit of formula IV wherein B represents an oxygen atom, E′ is adirect link, G represents a direct link, Ar represents a moiety ofstructure (iv), m and s represent zero, w represent 1, A and B represent1;

(h) a unit of formula V wherein E and E′ represent oxygen atoms, Grepresents a direct link, Ar represents a moiety of structure (iv), mrepresents 1, z represents 1, v represents 0, C and D represent 1; and

(i) a unit of formula V wherein E represents an oxygen atom, E′represents a direct link, G represents a direct link, Ar represents amoiety of structure (iv), m and v represent zero, z represents 1, C andD represent 1;

Other second units which may form copolymers with any of said firstrepeat units (a) to (e) (and/or with units (aa), (bb) and (cc)) aboveinclude: a unit of formula IV wherein E and E′ represent oxygen atoms, Grepresents a direct link, Ar represents a moiety of structure (v), mrepresents 0, w represents 1, s represents 0, A and B represent 1; or aunit of formula V wherein E and E′ represent oxygen atoms, G representsa direct link, Ar represents a moiety of structure (v), m represents 0,z represents 1, v represents 0, C and D represent 1.

Preferred first materials for some situations may comprise first unitsselected from (a), (b), (c) and (e) and second units selected from (f),(g), (h) or (i). A polymer comprising units (d) and (h) may also bepreferred. In some situations, first units may be selected from (aa),(bb) and (cc) and second units may be selected from (f), (g), (h) or(i).

More preferred first materials are copolymers having a first repeat unitselected from those described above, especially repeat units (b), (d) or(e) in combination with a second repeat unit selected from units (f) or(h). Other particularly preferred polymers are copolymers having a firstrepeat unit selected from (aa) and (bb) in combination with a secondrepeat unit selected from (f) or (h).

Preferred first materials having repeat unit(s) of formulae IV* and V*may include: a unit of formula IV* wherein Ar represents a moiety ofstructure (v), E represents a direct link, E′ represents an oxygen atom,G represents a direct link, w, s and m represent 0, A and B represent 1;and/or a repeat unit of formula V* wherein Ar represents a moiety ofstructure (v), E represents a direct link, E′ represents an oxygen atom,G represents a direct link, z, v and m represent 0, C and D represent 1.

Said first materials having repeat units IV* and V* may include any ofrepeat units (a) to (i) (and/or units (aa), (bb) and (cc)) describedabove.

In some situations, first materials which include at least one repeatunit of formula IV or formula IV* may be preferred.

Copolymers may be prepared having one or more first repeat units and oneor more of said second repeat units.

Where said first material is a copolymer as described, the mole % ofco-monomer units, for example said first and second repeat unitsdescribed above, may be varied to vary the solubility of the polymer insolvents, for example in organic solvents which may be used in thepreparation of films and/or membranes from the polymers and/or in othersolvents, especially water. Also, the mole % of co-monomer units may bevaried to vary the level of crystallinity and/or crystallisability. Forhomopolymers, the level of crystallinity and/or crystallisability may bedetermined by the level of functionalisation with ion-exchange sites.

Preferred first ion-conducting polymeric materials suitably have asolubility of at least 10% w/w, preferably a solubility in the range 10to 30% w/w in a polar aprotic solvent, for example NMP, DMSO or DMF.Preferred materials are substantially insoluble in boiling water aftertreatment with said crystallinity increasing means.

First units of the type described above (with the exception of units (a)and (c)) may be relatively difficult to sulphonate, whereas second unitsof the type described may be easier to sulphonate.

Where a phenyl moiety is sulphonated, it may only be mono-sulphonated.However, in some situations it may be possible to effect bi- ormulti-sulphonation.

In general terms, where a said first material includes a —O-phenyl-O—moiety, up to 100 mole % of the phenyl moieties may be sulphonated.Where a said first material includes a —O-biphenylene-O— moiety, up to100 mole % of the phenyl moieties may be sulphonated. It is believed tobe possible to sulphonate relatively easily —O-(phenyl)_(n)-O— moietieswherein n is an integer, suitably 1–3, at up to 100 mole %. Moieties offormula —O-(phenyl)_(n)-CO— or —O-(phenyl)_(n)-SO₂— may also besulphonated at up to 100 mole % but more vigorous conditions may berequired. Moieties of formulae —CO-(phenyl)_(n)-CO— and—SO₂-(phenyl)_(n)—SO₂— are more difficult to sulphonate and may besulphonated to a level less than 100 mole % or not at all under somesulphonation conditions.

The glass transition temperature (T_(g)) of said first material may beat least 144° C., suitably at least 150° C., preferably at least 154°C., more preferably at least 160° C., especially at least 164° C. Insome cases, the Tg may be at least 170° C., or at least 190° C. orgreater than 250° C. or even 300° C.

Said first material may have an inherent viscosity (IV) of at least 0.1,suitably at least 0.3, preferably at least 0.4, more preferably at least0.6, especially at least 0.7 (which corresponds to a reduced viscosity(RV) of least 0.8) wherein RV is measured at 25° C. on a solution of thepolymer in concentrated sulphuric acid of density 1.84 gcm⁻³, saidsolution containing 1 g of polymer per 100 cm⁻³ of solution. IV ismeasured at 25° C. on a solution of polymer in concentrated sulphuricacid of density 1.84 gcm³, said solution containing 0.1 g of polymer per100 cm³ of solution.

The measurements of both RV and IV both suitably employ a viscometerhaving a solvent flow time of approximately 2 minutes.

The main peak of the melting endotherm (Tm) for said first material maybe at least 300° C.

Said first ion-conducting polymeric material may include a crystallineor crystallisable unit which is of general formula IV or IV* asdescribed above, provided said unit is crystallisable. Suitably, to becrystallisable, said second unit does not include any Ar group offormula (ii), (viii), (ix) or (x). More preferably, it may also notinclude an AR group of formula (v), (vi) or (vii). Preferred Ar groupsconsist of one or more phenyl groups in combination with one or morecarbonyl and/or ether groups.

Said ion-conducting material, for example membrane of said first aspectmay comprise a single material which may define a PEM of, for example, afuel cell. In this event, therefore, a catalyst material may contactsaid single material on opposite sides thereof. Preferably, however,said ion-conducting membrane is a composite membrane which includes saidfirst ion-conducting polymeric material together with another material(hereinafter “said composite membrane material”).

The first ion-conducting material may be associated with said compositemembrane material to form a composite membrane in a variety of ways. Forexample, said first ion-conducting material in the form of anunsupported conductive polymer film can be contacted with, for examplelaminated to, said composite membrane material. Alternatively (andpreferably), one of either said composite membrane material or saidfirst ion-conducting material may be porous and the other one of eithersaid composite membrane material or said first ion-conducting materialmay be impregnated in the porous material.

Said composite membrane material may be a support material forsupporting said first ion-conducting polymeric material. In this case,said composite membrane material preferably is stronger and/or has alower water absorbance compared to said first ion-conducting material.

Alternatively, said first ion-conducting polymeric material may be asupport for the composite membrane material. In a further alternative,said first ion-conducting polymeric material and said composite membranematerial may define a homogenous mixture.

Examples of composite membrane materials include:

-   (A) materials comprising or, preferably consisting essentially of,    polytetrafluoroethylene, suitably provided as a porous film. Such a    support material may be as described in accordance with WO97/25369    and WO96/28242 and the contents of the aforementioned documents as    regards the polytetrafluoroethylene are incorporated herein by    reference; and surface modified polytetrafluoro-ethylene.-   (B) optionally-substituted polyolefins, especially    optionally-substituted polypropylene or polyethylene and copolymers    of any of the aforesaid.-   (C) Lyotropic liquid crystalline polymers, such as a polybenzazole    (PBZ) or polyaramid (PAR or Kevlar®) polymer. Preferred    polybenzazole polymers include polybenzoxazole (PBO),    polybenzothiazole (PBT) and polybenzimidazole (PBI) polymers.    Preferred polyaramid polymers include polypara-phenylene    terephthalamide (PPTA) polymers. Structures of the above-mentioned    polymers are listed in Table 4 of WO99/10165, the contents of which    are incorporated herein by reference.-   (D) Polysulfone (PSU), polyimide (PI), polyphenylene oxide (PPO),    polyphenylene sulphoxide (PPSO), polyphenylene sulphide (PPS),    polyphenylene sulphide sulphone (PPS/SO₂), polyparaphenylene (PPP),    polyphenylquinoxaline (PPQ), polyarylketone, polyethersulphone (PES)    and polyetherketone and polyetheretherketone polymers, for example    PEK™ polymers and PEEK™ polymers respectively from Victrex Plc.-   (E) Polymers have moieties I, II and/or III as described above for    said first ion-conducting polymeric material, except that such    polymers may be crystallisable, crystalline or amorphous and are not    functionalised to provide ion-exchange sites.-   (F) polymers described in (E), wherein at least some units I, II    and/or III are functionalized to provide ion-exchange sites suitably    of a type described herein with reference to said first    ion-conducting polymeric material.-   (G) Polymers described in (D) which are functionalized, especially    sulphonated, to provide ion-exchange sites, as described in    WO99/10165.-   (H) Perfluorinated ionomers, for example carboxyl-, phosphonyl- or    sulphonyl-substituted perfluorinated vinyl ethers as described in    WO99/10165. An especially preferred example is NAFION (Trade Mark)—a    perfluorosulphonate ionomer described in Journal of Electrochemical    Society, Vol 132, pp 514–515 (1985).-   (I) Ion-conductive polymers comprising α,β,β-trifluorostyrene    monomeric units as described in WO97/25369, the content of which is    incorporated herein by reference.-   (J) Ion-conducting polymers comprising polystyrene sulphonic acid    (PSSA), polytrifluorostyrene sulphonic acid, polyvinyl phosphonic    acid (PVPA), polyvinyl carboxylic (PVCA) acid and polyvinyl    sulphonic acid (PVSA) polymers, and metals salts thereof.

Where said composite membrane material is as described in (E) or (F))above, in some embodiments it may have at least some crystallinity ormay be crystallisable. In this event, the method of said first aspectmay include the step of treating said composite membrane material with asaid crystallinity increasing means as described above with reference tosaid first ion-conducting polymeric material.

When the composite membrane material is not an ion-conducting materialit preferably acts as a support for said first ion-conducting polymericmaterial. The ion-conducting material may be associated with thecomposite membrane material in a variety of ways. The method may involvelaminating said first ion-conducting material and said compositemembrane material together. Preferably, however, the method includesimpregnating porous composite membrane material with said firstion-conducting material.

Said porous composite membrane material may be a fabric or a microporousmembrane.

Where said composite membrane material is a fabric, the method mayinclude a step of contacting the fabric with a first solvent formulationcomprising a first solvent and said first ion-conducting material,wherein the first ion-conducting material is preferably dissolved in afirst solvent. Said fabric may, therefore, be impregnated with saidformulation. Thereafter, said first solvent may be removed, leaving saidconductive polymer in pores of said fabric.

Said first solvent and said porous composite membrane material may beselected so that said first solvent solubilises, to some degree, asurface of the material. Said first solvent may be capable of dissolvingthe material to a level of at least 5 wt %. This may improve contactbetween the first ion-conducting material and said composite membranematerial. Optionally, said first solvent may be capable offunctionalizing (e.g. sulphonating) said composite membrane material toprovide ion-exchange site on a surface thereof as hereinbeforedescribed.

Said first solvent may be a polar aprotic solvent, for example NMP, ormay be a protic solvent. A polar aprotic solvent may not be capable ofsolubilising said composite membrane support material whereas a proticsolvent may be able to solubilize and, in some cases, functionalise(e.g. sulphonate) said material.

Where said first solvent is a protic solvent, said solvent preferablycomprises or consists essentially of a strong acid solvent. Said solventmay comprise at least 90%, preferably at least 95%, more preferably atleast 97%, especially at least 98% acid. Said strong acid solvent may beone or more of sulphuric acid, a sulphonic acid (e.g. methane sulphonicacid, trichloromethane sulphonic acid, trifluoromethane sulphonic acid),hydrofluoric acid and phosphoric acid.

Preferably, a said protic first solvent comprises or consistsessentially of sulphuric acid. Said solvent may include at least 96%,preferably at least 98% acid. Said solvent may include less than 99%acid. A said protic first solvent is preferably arranged to sulphonateeasy to sulphonate units described herein, but not difficult tosulphonate units

Where said composite membrane material is a microporous membrane, themethod may include the step of contacting the microporous membrane witha first solvent formulation comprising a first solvent and said firstion-conducting material, wherein the first material is preferablydissolved in said first solvent. Said microporous membrane may,therefore, be impregnated with said formulation. Thereafter, said firstsolvent may be removed, leaving said conductive polymer in pores in saidmicroporous membrane.

Where said composite membrane material is a microporous membrane,preparation of the membrane may include a step of contacting a compositemembrane material with a solvent formulation comprising said firstsolvent. Said first solvent preferably solubilizes, to some degree, thecomposite membrane material. Said first solvent may be as describedabove with reference to the treatment of said fabric. Subsequently, themethod preferably includes the step of contacting the composite membranematerial with a second solvent. Said second solvent is preferablyarranged to cause phase inversion. Phase inversion suitably results insaid composite membrane material being rendered porous. Said secondsolvent is preferably a non-solvent for said material. Preferred secondsolvents are aqueous; especially preferred is water.

Said microporous composite membrane material is preferably contactedwith said first ion-conducting material so that said polymer penetratesinto pores formed in said composite membrane material. Said firstion-conducting polymer may be contacted with said composite membranematerial after pores have been formed therein, suitably by phaseinversion as described. In this regard, said first ion-conductingpolymer may be provided in a solvent, which may have the same identityas said first solvent described above. Such a combination may becontacted with a microporous membrane prepared as described toimpregnate pores of the membrane with said first ion-conducting polymer.

After deposition of said first ion-conducting polymer in pores, asdescribed above, the arrangement may be post-treated, suitably so as toproduce a substantially continuous film of said ion-conducting polymeron the composite membrane material. Post-treatment may include the stepof contacting the arrangement comprising first ion-conducting polymer inpores of said composite membrane material with a third solvent in whichsaid first ion-conducting polymer is relatively soluble and saidcomposite membrane material is substantially insoluble. This may causesome dissolution of the first ion-conducting polymer in the poresresulting in Film formation by coalescence of material between pores.Optionally, a said ion-conducting polymer may be provided in said thirdsolvent, thereby to deposit a layer of said ion-conducting polymer onthe surface of said composite membrane material. Said third solvent mayhave the same identity as said first solvent described above. Said thirdsolvent is preferably a polar aprotic solvent. NMP is a suitablesolvent.

When the composite membrane material is an ion-conducting materialeither said composite membrane material or said first ion-conductingmaterial may act as a support for the other one of either theion-conducting material or membrane material; or, alternatively, saidcomposite membrane material and said first ion-conducting material maybe mixed together, for example to define a substantially homogenousalloy as described in U.S. Pat. No. 5,834,566.

Where the composite membrane material provides a support for the firstion-conducting material, an ion-conducting membrane may be prepared asdescribed above with reference to the preparation of an ion-conductingmembrane comprising a composite membrane material which is not anion-conducting material and said first ion-conducting polymericmaterial. Where, however, the first ion-conducting polymeric materialprovides a support for composite membrane material which ision-conducting, an ion-conducting membrane may be prepared as describedabove (with reference to the preparation of the ion-conducting membraneof composite membrane material which comprises non-ion conductingmaterial together with said first ion-conducting polymeric material)except that the reference to composite membrane material in saiddescription should be replaced with a reference to said firstion-conducting material and said reference to said first ion-conductingpolymeric material should be replaced with a reference to said compositemembrane material which is ion-conducting.

The method preferably includes the step of preparing a precursormaterial, for example membrane which includes said first ion-conductingpolymeric material and, subsequently, treating said precursor material,for example membrane with said crystallinity increasing means thereby toprepare said ion-conducting material, for example membrane of reducedsensitivity to water. Treatment with said means may be carried out atany time after preparation of said precursor material, for examplemembrane.

Preferably, after treatment with said crystallinity increasing means,the solubility of said first ion-conducting polymeric material in asolvent in which said first ion-conducting material may have beendissolved in order to prepare said precursor material, for examplemembrane is reduced. It may be reduced to a level such that it would besubstantially impossible to cast a satisfactory material, for examplemembrane from the first ion-conducting material using said first solventafter treatment with said crystallinity increasing means.

Where the ion-conducting membrane includes a composite membrane materialwhich has at least some crystallinity or which is crystallisable, saidcomposite membrane material and said first ion-conducting polymericmaterial may be treated together with said crystallinity increasingmeans. Alternatively, after the composite membrane material has beenassociated with said first ion-conducting material to prepare aprecursor membrane, the combination may be treated independently with asaid crystallinity increasing means and said means may be the same ordifferent for the respective treatments. For example, in one embodiment,after the first ion-conducting material or said composite membranematerial has been formed into a film, it may be treated with saidcrystallinity increasing means. Then, the other one of said firstion-conducting material or said composite membrane material is contactedwith said treated material. In this respect, the treated material maysuitably be rendered porous as described herein and contacted.Thereafter, the as yet untreated first ion-conducting material orcomposite membrane material may be treated with a said crystallinityincreasing means.

In general terms, said first ion-conducting material may be arranged asfollows when associated with said composite membrane material to form acomposite membrane:

-   FC1—penetrating pores of the composite membrane material-   FC2—acting as a support material which is penetrated by said    composite membrane material.-   FC3—acting as a support material wherein it is surface    functionalised to provide ion-exchange sites (but the bulk of the    polymer is not functionalised).

Said composite membrane material may be arranged as follows whenassociated with said first ion-conducting polymer:

-   CM1—as a non-crystallisable and non-crystalline material which    penetrates pores of the composite membrane material.-   CM2—as a fabric (e.g. polyetheretherketone, polyetherketone,    polyetherdiphenyletherketone/polyetherketone.)-   CM3—as a non-sulphonated amorphous microporous membrane-   CM4—as a non-sulphonated semi-crystalline microporous membrane.

The combinations of first ion-conducting materials and compositemembrane material may be as follows:

-   1. FC1 only. Post treated to increase crystallinity-   2. FC1+CM2. Post treated to increase crystallinity (only FC1 will be    affected).-   3. FC1+CM3. Post treated to increase crystallinity (only FC1 will be    affected.-   4. FC1+CM4. Post treated to increase crystallinity (FC1 and CM4 will    be affected).-   5. FC1+CM4. CM4 is pre-treated to increase crystallinity. FC1 is    post treated.-   6. FC1+FC3. Post treated to increase crystallinity (FC1 and FC3 will    be affected).-   7. FC1+FC3. Surface functionalised FC3 pre-treated to increase    crystallinity. FC1 post treated to increase crystallinity.-   8. FC1+FC2. Post treated to increase crystallinity. (FC1 and FC1    will be affected).-   9. FC1+FC2. FC2 is pre-treated to increase crystallinity. FC1 is    post treated to increase crystallinity.-   10. CM1+CM4. Post treated to increase crystallinity (CM4 only will    be affected).-   11. CM1+CM4. CM4 is pre-treated to increase crystallinity.-   12. CM1+FC3. Post treated to increase crystallinity (surface    functionalised FC3 will be affected).-   13. CM1+FC3. Surface functionalised FC3 pre-treated to increase    crystallinity.-   14. CM1+FC2. Post treated to increase crystalllinity (FC2 will be    affected).-   15. CM1+FC2. FC2 is pre-treated to increase crystallinity.

The method may include a subsequent step of associating a catalystmaterial with said ion-conducting membrane prepared and suitablypreparing a MEA. The MEA may be for a hydrogen or Direct Methanol FuelCell.

The invention extends to any novel ion-conducting material, for examplemembrane described herein.

The invention extends to an ion-conducting material, for examplemembrane prepared in a method according to said first aspect.

The invention extends to a method of preparing a Membrane ElectrodeAssembly (MEA) which includes associating a catalyst material and/orelectrode with an ion-conducting membrane prepared according to saidfirst aspect.

The invention extends to any novel MEA described herein per se.

The invention extends to a MEA prepared in a method according to saidfirst aspect and/or described herein.

An ion-conducting material, for example membrane as described herein maybe used in fuel cells or electrolysers and, accordingly, the inventionextends to a fuel cell or electrolyser incorporating an ion-conductingmaterial, for example membrane prepared in a method according to saidfirst aspect and/or as described herein. The material, for examplemembrane may be used in Hydrogen Fuel Cells or Direct Methanol FuelCells. The membranes may also be used in filtration (as parts offiltration membranes), for example in ultrafiltration, microfiltrationor in reverse osmosis. The most preferred use is in a fuel cell asdescribed.

The following further utilities are also contemplated:

-   1. Proton exchange membrane based water electrolysis, which involves    a reverse chemical reaction to that employed in hydrogen/oxygen    electrochemical fuel cells.-   2. Chloralkali electrolysis, typically involving the electrolysis of    a brine solution to produce chlorine and sodium hydroxide, with    hydrogen as a by-product.-   3. Electrode separators in conventional batteries due to the    chemical inertness and high electrical conductivity of the composite    membranes.-   4. Ion-selective electrodes, particularly those used for the    potentiometric determination of a specific ion such as Ca²⁺, Na⁺, K⁺    and like ions. The composite membrane could also be employed as the    sensor material for humidity sensors, as the electrical conductivity    of an ion exchange membrane varies with humidity.-   5. Ion-exchange material for separations by ion-exchange    chromatography. Typical such applications are deionization and    desalination of water (for example, the purification of heavy metal    contaminated water), ion separations (for example, rare-earth metal    ions, trans-uranium elements), and the removal of interfering ionic    species.-   6. Ion-exchange membranes employed in analytical preconcentration    techniques (Donnan Dialysis). This technique is typically employed    in analytical chemical processes to concentrate dilute ionic species    to be analysed.-   7. Ion-exchange membranes in electrodialysis, in which membranes are    employed to separate components of an ionic solution under the    driving force of an electrical current. Electrolysis applications    include the industrial-scale desalination of brackish water,    preparation of boiler feed make-up and chemical process water,    de-ashing of sugar solutions, deacidification of citrus juices,    separation of amino acids, and the like.-   8. Membranes in dialysis applications, in which solutes diffuse from    one side of the membrane (the feed side) to the other side according    to their concentration gradient. Separation between solutes is    obtained as a result of differences in diffusion rates across the    membrane arising from differences in molecular size. Such    applications include hemodialysis (artificial kidneys) and the    removal of alcohol from beer.-   9. Membranes in gas separation (gas permeation) and pervaporation    (liquid permeation) techniques.-   10. Bipolar membranes employed in water splitting and subsequently    in the recovery of acids and bases from waste water solutions.

Polymers having units I, II, III, IV, IV*, V and/or V* may be preparedby:

(a) polycondensing a compound of general formula

with itself wherein Y¹ represents a halogen atom or a group —EH and Y²represents a halogen atom or, if Y¹ represents a halogen atom, Y²represents a group E′H; or

(b) polycondensing a compound of general formula

with a compound of formula

and/or with a compound of formula

wherein Y¹ represents a halogen atom or a group —EH (or —E′H ifappropriate) and X¹ represents the other one of a halogen atom or group—EH (or —E′H if appropriate) and Y² represents a halogen atom or a group—E′H and X² represents the other one of a halogen atom or a group —E′H(or —EH if appropriate).

(c) optionally copolymerizing a product of a process as described inparagraph (a) with a product of a process as described in paragraph (b);

wherein the phenyl moieties of units VI, VII and/or VIII are optionallysubstituted; the compounds VI, VII and/or VIII are optionallysulphonated; and Ar, m, w, r, s, z, t, v, G, E and E′ are as describedabove except that E and E′ do not represent a direct link;

the process also optionally comprising sulphonating and/or cross-linkinga product of the reaction described in paragraphs (a), (b) and/or (c) toprepare said polymer.

In some situations, the polymer prepared, more particularly phenylgroups thereof, may be optionally substituted with the groupshereinabove described after polymer formation.

Preferably, where Y¹, Y², X¹ and/or X² represent a halogen, especially afluorine, atom, an activating group, especially a carbonyl or sulphonegroup, is arranged ortho- or para- to the halogen atom.

Preferred halogen atoms are fluorine and chlorine atoms, with fluorineatoms being especially preferred. Preferably, halogen atoms are arrangedmeta- or para- to activating groups, especially carbonyl groups.

Where the process described in paragraph (a) is carried out, preferablyone of Y¹ and Y² represents a fluorine atom and the other represents anhydroxy group. More preferably in this case, Y¹ represents a fluorineatom and Y² represents an hydroxy group. Advantageously, the processdescribed in paragraph (a) may be used when Ar represents a moiety ofstructure (i) and m represents 1.

When a process described in paragraph (b) is carried out, preferably, Y¹and Y² each represent an hydroxy group. Preferably, X¹ and X² eachrepresent a halogen atom, suitably the same halogen atom.

The polycondensation reaction described is suitably carried out in thepresence of a base, especially an alkali metal carbonate or bicarbonateor a mixture of such bases. Preferred bases for use in the reactioninclude sodium carbonate and potassium carbonate and mixtures of these.

The identity and/or properties of the polymers prepared in apolycondensation reaction described may be varied according to thereaction profile, the identity of the base used, the temperature of thepolymerisation, the solvent(s) used and the time of the polymerisation.Also, the molecular weight of a polymer prepared controlled by using anexcess of halogen or hydroxy reactants, the excess being, for example,in the range 0.1 to 5.0 mole %

In a polymer prepared in a said polycondensation reaction involvingcompounds of general formula VI, VII, and VIII, moieties of generalformula VI, VII, and VIII (excluding end groups Y¹, Y², X¹ and X²) maybe present in regular succession (that is, with single units of one saidmoiety, separated by single units of another said moiety or moieties),or semi-regular succession (that is, with single units of one saidmoiety separated by strings of another moiety or moieties which are notall of the same length) or in irregular succession (that is, with atleast some multiple units of one moiety separated by strings of othermoieties that may or may not be of equal lengths). The moietiesdescribed are suitably linked through ether or thioether groups.

Also, moieties in compounds VI, VII and VIII arranged between a pair ofspaced apart —O— atoms and which include a -phenyl-SO₂ or -phenyl-CO—bonded to one of the —O— atoms may, in the polymer formed in thepolycondensation reaction, be present in regular succession,semi-regular succession or in irregular succession, as describedpreviously.

In any sampled polymer, the chains that make up the polymer may be equalor may differ in regularity from one another, either as a result ofsynthesis conditions or of deliberate blending of separately madebatches of polymer.

Compounds of general formula VI, VII and VIII are commercially available(eg from Aldrich U.K.) and/or may be prepared by standard techniques,generally involving Friedel-Crafts reactions, followed by appropriatederivatisation of functional groups. The preparations of some of themonomers described herein are described in P M Hergenrother, B J Jensenand S J Havens, Polymer 29, 358 (1988), H R Kricheldorf and U Delius,Macromolecules 22, 517 (1989) and P A Staniland, Bull, Soc, Chem, Belg.,98 (9–10), 667 (1989).

Where compounds VI, VII and/or VIII are sulphonated, compounds offormulas VI, VII and/or VIII which are not sulphonated may be preparedand such compounds may be sulphonated prior to said polycondensationreaction.

Sulphonation as described herein may be carried out in concentratedsulphuric acid (suitably at least 96% w/w, preferably at least 97% w/w,more preferably at least 98% w/w; and preferably less than 98.5% w/w) atan elevated temperature. For example, dried polymer may be contactedwith sulphuric acid and heated with stirring at a temperature of greaterthan 40° C., preferably greater than 55° C., for at least one hour,preferably at least two hours, more preferably about three hours. Thedesired product may be caused to precipitate, suitably by contact withcooled water, and isolated by standard techniques. Sulphonation may alsobe effected as described in U.S. Pat. No. 5,362,836 and/or EP0041780.

Any feature of any aspect of any invention or embodiment describedherein may be combined with any feature of any aspect of any otherinvention or embodiment described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments of the invention will now be described, by way ofexample, with reference to FIG. 1 which is a schematic representation ofa polymer electrolyte membrane fuel cell.

Unless otherwise stated, all chemicals referred to hereinafter were usedas received from Sigma-Aldrich Chemical Company, Dorset, U.K.

EXAMPLES Example 1a

A 700 ml flanged flask fitted with a ground glass Quickfit lid,stirrer/stirrer guide, nitrogen inlet and outlet was charged with4,4′-difluorobenzophenone (89.03 g, 0.408 mole) (BDF),4,4′-dihydroxybiphenyl (24.83, 0.133 mole),4,4′-dihydroxydiphenylsulphone (13.35 g, 0.053 mole) (Bis-S),4,4′-dihydroxybenzophenone (45.7 g, 0.213 mole) (DHB) anddiphenysulphone (332 g) and purged with nitrogen for over 1 hour. Thecontents were then heated under a nitrogen blanket to between 140 and150° C. to form an almost colourless solution. While maintaining anitrogen blanket, dried sodium carbonate (43.24 g, 0.408 mole) wasadded. The temperature was raised gradually to 320° C. over 3 hours thenmaintained for 1.5 hours.

The reaction mixture was allowed to cool, milled and washed with acetoneand water. The resulting polymer was dried in an air oven at 120° C. Thepolymer had a melt viscosity at 400° C., 1000 sec⁻¹ of 0.39 kNsm⁻².

Examples 1b–1e and 1f (Comparative)

The polymerisation procedure of Example 1a was followed, for 1b–1e,except that copolymers were prepared by varying the mole ratios of thehydroxy-containing reactants. The polymerisation procedure for 1f isdescribed below.

A 700 ml flanged flask-fitted with a ground glass Quickfit lid,stirrer/stirrer guide, nitrogen inlet and outlet was charged with4,41-difluorobenzophenone (89.03 g, 0.408 mole), 4,4′-dihydroxybiphenyl(24.83 g, 0.133 mole) 4,41-dihydroxydiphenylsulphone (66.73 g, 0.267mole), and diphenysulphone (332 g) and purged with nitrogen for over 1hour. The contents were then heated under a nitrogen blanket to between140 and 150° C. to form an almost colourless solution. While maintaininga nitrogen blanket, dried sodium carbonate (42.44 g, 0.4 mole) andpotassium carbonate (1.11 g, 0.008 mole) were added. The temperature wasraised gradually to 315° C. over 3 hours then maintained for 0.5 hours.

The reaction mixture was allowed to cool, milled and washed with acetoneand water. The resulting polymer was dried in an air oven at 120° C. Thepolymer had a melt viscosity at 400° C., 1000 sec⁻¹ of 0.62 kNsm⁻²

A summary of the mole ratios and MVs are detailed in the Table below.Example 1f is an amorphous equivalent of the other polymers.

Polymer Composition (mole ratio) MV Example BDF BP DHB Bis-S (kNsm⁻²) 1a1.02 0.33 0.533 0.133 0.37 1b 1.02 0.33 0.402 0.268 0.47 1c 1.02 0.330.335 0.335 0.48 1d 1.02 0.33 0.268 0.402 0.48 1e 1.02 0.33 0.133 0.5360.53 1f 1.02 0.33 — 0.67  0.62

Examples 2a–2e and 2f (Comparative)

The polymers from Examples 1a –1f were sulphonated by stirring therespective polymers in 98% sulphuric acid (3.84 g polymer/100 gsulphuric acid) for 21 hours at 50° C. Thereafter, the reaction solutionwas allowed to drip into stirred deionised water. Sulphonated polymerprecipitated as free-flowing beads. Recovery was by filtration, followedby washing with deionised water until the pH was neutral and subsequentdrying. In general, titration confirmed that 100 mole % of the biphenylunits had sulphonated, giving one sulphonic acid group, ortho to theether linkage, on each of the two aromatic rings comprising the biphenylunit.

Examples 3a-3e and 3f (Comparativ )

Membrane Fabrication

Membranes were produced from the sulphonated polymers of respectiveExamples 2a–2f by dissolving respective polymers in N-methylpyrrolidone(NMP). The polymers were dissolved at 80° C. at their maximumconcentration. In one example, a 50:50 w/w blend of the polymersdescribed in Examples 3d and 3e, sulphonated as described in Example 2,was used to prepare a membrane. The homogeneous solutions were cast ontoclean glass plates and then drawn down to give 400 micron films, using astainless steel Gardner Knife. Evaporation at 100° C. under vacuum for24 hours produced membranes of mean thickness 40 microns.

Examples 4a–4e and 4f (Comparative)

Water-Uptake of the Membranes

5 cm×5 cm×40 microns sample of the membranes from Example 3a–3f wereimmersed in boiling deionised water (500 ml) for 60 mins, removed anddried quickly with lint-free paper to remove surface water, weighed,dried in an oven at 50° C. for 1 day, allowed to cool to ambienttemperature in a desiccator then weighed quickly. The % water-uptake wascalculated as follows and the results are provided in the Tablepresented in Example 6.

${\%\mspace{14mu}{Water}\text{-}{uptake}} = {\frac{{{Wet}\mspace{14mu}{Weight}} - {{Dry}\mspace{14mu}{Weight}}}{{Dry}\mspace{14mu}{Weight}} \times 100}$

Example 5

Post Treatment of the Membrane with Dichloromethane

The 5 cm×5 cm×40 microns sample of membrane from Example 4a was immersedin dichloromethane (100 ml) for 60 mins, removed and dried in an oven at50° C. for 1 day. Immersed in boiling deionised water (500 ml) for 60mins, removed and dried quickly with lint-free paper to remove surfacewater, weighed, dried in an oven at 50° C. for 1 day, allowed to cool toambient temperature in a desiccator then weighed quickly. The %water-uptake was 35%, as calculated previously.

Example 6a

Post Treatment of the Membranes from 4a–4f with Acetone.

The procedure of Example 5 was followed, except that the membranes fromExamples 3a–3f were immersed in refluxing acetone. The % water-uptake ofeach membrane was as calculated previously and summarised in the Tablebelow.

Boiling Boiling Water Water uptake uptake Sulphonated before afterpolymer acetone acetone Actual EW from treatment treatment Theoretical(by Example (%) (%) EW titration) 3a 69 61 657 3b 77 48 663 667 3c 81 57670 671 3d 90 63 676 685 3e 172 100 683 663 3f 165 170 690 660 50:50 w/w128 73 blend of polymers from Examples 3d and 3e

Example 6b

Determination of the Crystallinity Index Values of Sulphonated Polymersfrom Examples 1b, 1d and 1f Before and After Acetone Treatment by WideAngle X-Ray Scattering (WAXS)

Crystallinity can be quantified, in one method, by defining a“crystallinity index” for measurements made by Wide Angle X-rayScattering (WAXS). This approach defines the measurement in relation tothe WAXS pattern. The measured area of crystalline peaks in the WAXSpattern is taken as a percentage of the total crystalline and amorphousscatter over a chosen angular range of the pattern. Crystallinity indexshould, to a first approximation, be proportional to crystallinity forbroadly similar polymer materials. It is constrained to be zero whencrystallinity is zero and 100% when crystallinity is 100%.

Membranes of the sulphonated polymers from Examples 1b, 1d and 1f asprepared in Example 3b, 3d and 3f and post treated with acetone asdescribed in Example 6 were examined by WAXS as described below.

The membranes were analysed using a Siemens D5000 X-ray diffractometerwith Cu K-alpha radiation and a Kevex energy dispersive detector.Measurements were made from a single membrane sheet mounted insymmetrical reflection geometry. A programmable divergence slit was usedto maintain a constant irradiated region of the specimen surface 6 mmlong over a 2-theta measurement range of 10–49°.

The WAXS pattern of the membrane from Example 1f before and afteracetone treatment exhibited only broad amorphous scatter, whereas thepatterns of the membranes from Examples 1b and 1d, before and afteracetone treatment exhibited sharper, crystalline peaks in addition toamorphous bands.

The measured WAXS patterns were analysed by first making a backgroundcorrection, subtracting the corresponding WAXS pattern from a blankspecimen holder. The resulting patterns were fitted by a combination ofa pattern measured from a similar but amorphous membrane film and a setof peaks (at approximately 18.8, 20.8, 22.9, 29.1 and 40.0° 2-theta)corresponding to those observed in the more crystalline membranes. Thecrystallinity index was calculated as the total area fitted by thesepeaks taken as a percentage of the combined area of the fitted peaks andthe fitted amorphous pattern.

The results are detailed in the Table below.

Crystallinity Index (%) Sulphonated polymer Before acetone After acetonefrom Example treatment treatment 1f 0 0 1d 2 5.5 1b 7 9

Example 7a

A 700 ml flanged flask fitted with a ground glass Quickfit lid,stirrer/stirrer guide, nitrogen inlet and outlet was charged with4,4′-difluorobenzophenone (89.03 g, 0.408 mole), 4,4′-dihydroxybiphenyl(29.79 g, 0.16 mole), 4,4′-dihydroxydiphenylsulphone (36.04 g, 0.144mole), 4,4′-dihydroxybenzophenone (20.57 g, 0.096 mole) anddiphenysulphone (332 g) and purged with nitrogen for over 1 hour. Thecontents were then heated under a nitrogen blanket to between 140 and150° C. to form an almost colourless solution. While maintaining anitrogen blanket, dried sodium carbonate (43.24 g, 0.408 mole) wasadded. The temperature was raised gradually to 320° C. over 3 hours thenmaintained for 1.5 hours.

The reaction mixture was allowed to cool, milled and washed with acetoneand water. The resulting polymer was dried in an air oven at 120° C. Thepolymer had a melt viscosity at 400° C., 1000 sec⁻¹ of 0.6 kNsm⁻².

Examples 7b–7e and 7f (Comparative)

The polymerisation procedure of Example 7a was followed, except thatcopolymers were prepared by varying the mole ratios of thehydroxy-containing reactants. A summary of the mole ratios and the MVsare detailed in the Table below.

Actual EW Polymer Composition (mole ratio) MV Theoret- (by Example BDFBP DHB Bis-S (KNsm⁻²) ical EW titration) 7a 1.02 0.4 0.24 0.36 0.6  564564 7b 1.02 0.4 0.36 0.24 0.21 559 564 7c 1.02 0.4 0.39 0.21 0.32 558571 7d 1.02 0.4 0.42 0.18 0.44 557 591 7e 1.02 0.4 0.6  — 0.45 550 5727f 1.02 0.4 — 0.6  0.26 583 602

Examples 8a–8e and 8f (Comparative) Sulphonation and SubsequentDissolution of Polymers from Examples 7a–f

The polymers from Examples 7a–f were sulphonated as described in Example2, dissolved in NMP, filtered through a 10 micron filter, cast on toclean glass plates and drawn down, using a Gardner Knife. The solventwas evaporated at 100° C. under vacuum for 24 hours producing membranesof mean thickness of 40 microns. The boiling water uptake was determinedas described in Example 4. The results are detailed in the Tablepresented in Example 9.

Example 9a

Post Treatment of the Membranes from 8a –8f with Acetone.

The procedure of Example 5 was followed, except that the membranes fromExamples 8a–8f were immersed in refluxing acetone. The % water-uptake ofeach membrane was calculated as described in Example 4. The results aresummarised in the Table below.

Boiling Water Boiling Water Sulphonated uptake before uptake beforepolymer from acetone acetone Example treatment (%) Treatment (%) 8a 550130 8b 190 97 8c 135 81 8d 109 58 8e 82 69 8f 520 520

Example 9b

Determination of the Crystallinity Index Values of Sulphonated Polymersfrom Examples 9c and 9f by WAXS

Membranes of the sulphonated polymers from Examples 7c and 7f asprepared in Examples 8c and 8f and post treated with acetone in Example9 were examined by WAXS as described in the previous Example.

The WAXS pattern of the membrane from Example 7f before and afteracetone treatment exhibited only broad amorphous scatter, whereas thepatterns of the membrane from Examples 7c before and after acetonetreatment exhibited sharper, crystalline peaks in addition to amorphousbands.

The results are detailed in the Table below.

Crystallinity Index (%) Sulphonated polymer Before acetone After acetonefrom Example treatment treatment 7f 0 0 7c 6 12

Examples 10a–10d

Sulphonation of Polyetherketone and Subsequent Dissolution

A 500 ml, 3-necked, round-bottomed flask fitted with a stirrer/stirrerguide, nitrogen inlet and outlet and a thermometer was charged with 98%sulphuric acid (180 g) and, while stirring, polyetherketone (PEK™ P22,Victrex plc) (20 g) was added. The temperature was increased to 55° C.and oleum (20% free SO₃) (120 g) was added. The solution was stirred for60 minutes at 55° C. The solution was quickly cooled to 20° C.,thereafter, allowed to drip into stirred deionised water. Sulphonatedpolymer precipitated as free-flowing beads. Recovery was by filtration,followed by washing with deionised water until the pH was neutral andsubsequent drying. By titration the Equivalent Weight was 476.

The above procedure was repeated three times except that thesulphonating solution was heated to 35° C. before oleum was added andmaintained at that temperature for 60 mins before being rapidly cooledto 20° C. The Equivalent Weights of the sulphonated polymers was 568,667 and 758.

The sulphonated polyetherketone polymers described above were separatelydissolved in NMP, filtered through a 10 micron filter, cast on to cleanglass plates and drawn down, using a Gardner Knife. The solvent wasevaporated at 100° C. under vacuum for 24 hours producing membranes ofmean thickness of 40 microns. The boiling water uptake was determined asdescribed in Example 4. The results are detailed in the Table presentedin Example 11.

Example 11

Post Treatment of the Membranes from 10a–10d with Acetone.

The procedure of Example 5 was followed, except that the membranes fromExamples 10a–10c were immersed in refluxing acetone. The % water-uptakeof each membrane was calculated as described in Example 4 and summarisedin the Table below.

Boiling Water Boiling Water Sulphonated uptake before uptake afterpolymer from acetone acetone Example EW treatment (%) Treatment (%) 10a476 Sample broke 124 up 10b 568 950 72 10c 670 370 56 10d 758  80 51

Example 12a

A 700 ml flanged flask fitted with a ground glass Quickfit lid,stirrer/stirrer guide, nitrogen inlet and outlet was charged with4,4′-difluorobenzophenone (89.03 g, 0.408 mole) 4,4′-dihydroxybiphenyl(24.83 g, 0.133 mole), 2,4-dihydroxybenzophenone (11.42 g, 0.053 mole),4,4′-dihydroxybenzophenone (45.7 g, 0.213 mole) and diphenysulphone (332g) and purged with nitrogen for over 1 hour. The contents were thenheated under a nitrogen blanket to between 140 and 150° C. to form analmost colourless solution. While maintaining a nitrogen blanket, driedsodium carbonate (43.24 g, 0.408 mole) was added. The temperature wasraised gradually to 320° C. over 3 hours then maintained for 1.5 hours.

The reaction mixture was allowed to cool, milled and washed with acetoneand water. The resulting polymer was dried in an air oven at 120° C. Thepolymer had a melt viscosity at 400° C., 1000 sec⁻¹ of 0.80 kNsm⁻².

Examples 12b and 12c

The polymerisation procedure of Example 12a was followed except thatcopolymers were prepared with a different mole ratio ofhydroxy-containing reactants. A summary of the mole ratios and MVs forExamples 12a, 12b and 12c are detailed in the table below.

Polymer Composition (mole ratio) MV Example BDF BP 4,4′-DHB 2,4-DHB(kNsm⁻²) 12a 1.02 0.33 0.533 0.133 0.70 12b 1.02 0.33 0.402 0.268 0.3812c 1.02 0.33 0.133 0.533 0.47

Example 13

The polymers of Example 12a, 12b and 12c were sulphonated, fabricatedinto membranes, assessed and post-treated with acetone as described inrespective examples 2, 3, 4 and 6 and the results are provided in thetable below.

Boiling Boiling Water Water Sulphon- Uptake Uptake ated Measured beforeafter polymer EW acetone acetone from Theoretical (by Concentrationtreatment treatment Example EW titration) in NMP (% w/w) (%) (%) 12a 647666  5  73 58 12b 655 671 10 100 69 12c 670 681 15 518 208 

Example 14

A 250 ml 3-necked, round-bottomed fitted with a stirrer/stirrer guide,nitrogen inlet and outlet was charged with 4,41-difluorobenzophenone(11.36 g, 0.052 mole), 4,4′-bis (4-chlorophenylsulphonyl)biphenyl (LCDC)(25.17 g, 0.05 mole), 4,4′-dihydroxybiphenyl (6.21 g, 0.0333 mole),4,4′-dihydroxybenzophenone (14.28 g, 0.0667 mole), and diphenysulphone(90 g) and purged with nitrogen for over 1 hour. The contents were thenheated under a nitrogen blanket to between 140 and 150° C. to form analmost colourless solution. While maintaining a nitrogen blanket, driedsodium carbonate (10.6 g, 0.1 mole) and potassium carbonate (0.28 g,0.002 mole) were added. The temperature was raised gradually to 315° C.over 3 hours then maintained for 1 hour.

The reaction mixture was allowed to cool, milled and washed with acetoneand water. The resulting polymer was dried in an air oven at 120° C. Thepolymer had a melt viscosity at 400° C., 1000sec⁻¹ of 0.18kNsm⁻².

Example 15

A 250 ml 3-necked, round-bottomed fitted with a stirrer/stirrer guide,nitrogen inlet and outlet was charged with 4,4′-difluorobenzophenone(11.02 g, 0.0505 mole), 4,41-dichlorodiphenylsulphone (14.36 g, 0.05mole), 4,4′-dihydroxybiphenyl (6.21 g, 0.0333 mole),4,4′-dihydroxybenzophenone (14.28 g, 0.0667 mole), and diphenysulphone(83 g) and purged with nitrogen for over 1 hour. The contents were thenheated under a nitrogen blanket to between 140 and 150° C. to form analmost colourless solution. While maintaining a nitrogen blanket, driedsodium carbonate (10.60 g, 0.1 mole) and potassium carbonate (0.28 g,0.002 mole) were added. The temperature was raised gradually to 315° C.over 3 hours then maintained for 140 minutes.

The reaction mixture was allowed to cool, milled and washed with acetoneand water. The resulting polymer was dried in an air oven at 120° C. Thepolymer had a melt viscosity at 400° C., 1000 sec⁻¹ of 0.39 kNsm⁻².

Example 16

Sulphonation of and Subsequent Dissolution and Membrane Fabrication ofPolymers from Examples 14 and 15

The polymers from Examples 14 and 15 were sulphonated as described inExample 2 and separately dissolved in NMP at 15% w/w at 80° C. and roomtemperature respectively. The homogeneous solutions were filteredthrough a 10 micron filter, cast on to clean glass plates and drawn downto give 400 micron films, using a Gardner Knife. The solvent wasevaporated at 100° C. under vacuum for 24 hours. The boiling wateruptake was determined for each membrane as described in Example 4. Theresults are detailed in the Table below.

Boiling Boiling Water Water Sulphon- Uptake Uptake ated Measured beforeafter polymer EW acetone acetone from Theoretical (by Concentrationtreatment treatment Example EW titration) in NMP (% w/w) (%) (%) 14 830858 15  39 31 15 680 691 15 108 46

Example 17

Post Treatment of the Membranes from Examples 3e and 8a with THF.

The procedure of Example 5 was followed, except that the membranes fromExamples 3e and 8a were immersed in refluxing THF. The % water-uptake ofeach membrane was calculated as described in Example 4. The results aresummarised in the Table below.

Boiling Water Boiling Water Sulphonated uptake uptake polymer frombefore THF after THF Example treatment (%) treatment (%) 3e 172 115 8a550 143

Example 18a

A 700 flanged flask fitted with a ground glass Quickfit lid,stirrer/stirrer guide, nitrogen inlet and outlet was charged with4,4′-difluorobenzophenone (89.03 g, 0.408 mole), 4,4′-dihydroxybiphenyl(37.24 g, 0.20 mole) 4,4′-dihydroxybenzophenone (42.84 g, 0.20 mole),and diphenysulphone (332 g) and purged with nitrogen for over 1 hour.The contents were then heated under a nitrogen blanket to between 140and 150° C. to form an almost colourless solution. While maintaining anitrogen blanket, dried sodium carbonate (43.24 g, 0.408 mole) wasadded. The temperature was raised gradually to 330° C. over 3 hours thenmaintained for 1 hours.

The reaction mixture was allowed to cool, milled and washed with acetoneand water. The resulting polymer was dried in an air oven at 120° C. Thepolymer had a melt viscosity at 400° C., 1000 sec⁻¹ of 0.48 kNsm⁻².

Example 18b, 18c and 18d (Comparative)

Example 18a has a ratio of DHB:Bis-S of 100:0. Examples 18b –18d areprepared as described for Example 18a except the ratios of DHB:Bis-S are80:20, 70:30 and 0:100 respectively. The melt viscosities of thepolymers were 0.34 kNsm⁻², 0.42 kNsm⁻² and 0.43 kNsm⁻² respectively.

Example 19

The polymers of Examples 18a–18d were sulphonated, fabricated intomembranes, assessed and post-treated with acetone as described inrespective examples 2, 3, 4 and 6 and the results are provided in thetable below.

Boiling Boiling Water Water Uptake Uptake Sulphonated before afterpolymer EW Actual acetone acetone Example from (% w/w) EW (by treatmenttreatment No DHB:Bis-S Theorerical titration) (%) (%) 18a 100:0 458 472237 116 18b 80:20 462 483 300 125 18c 70:30 464 480 320 152 18d 0:100476 492 Soluble Soluble

Example 20

Sulphonation of Polyetheretherketone and Subsequent Dissolution

A 500 ml, 3-necked, round-bottomed flask fitted with a stirrer/stirrerguide, nitrogen inlet and outlet and a thermometer was charged with 98%sulphuric acid (180 g ). The sulphuric acid was heated under a blanketof nitrogen to 50° C. While maintaining a nitrogen blanket and stirringpolyetheretherketone (PEEK™ 450P, Victrex plc) was added. The polymerdissolved and was stirred at 50° C. for 90 minutes. The solution wasquickly cooled to 20° C., thereafter allowed to drip into stirreddeionised water. Sulphonated polymer precipitated as free-flowing beads.Recovery was by filtration, followed by washing with deionised wateruntil the pH was neutral and subsequent drying. By titration theEquivalent Weight was 644.

The sulphonated polymer described above was dissolved in NMP (15% w/w),filtered through 10 micron filter, cast on to a clean glass plate anddrawn down, using a Gardner Knife. The solvent was evaporated at 100° C.under vacuum for 24 hours producing a membrane of mean thickness of 40microns. In boiling water the membrane was swollen excessively and brokeinto pieces.

Example 21

Post Treatment of the Membrane from Example 20

The procedure of Example 5 was followed, except that the membrane fromExample 19 was immersed in refluxing acetone. In boiling water themembrane remained intact and the % water uptake was 127% as calculatedas described in Example 4.

Example 22

Blends with Polyethersulphone

The polymer from Example 1d, sulphonated as described andpolyethersulphone were dissolved in N-methylpyrrolidone (NMP) atconcentrations shown in the Table below. The homogeneous solutions werecast onto clean glass plates and then drawn down to give 400 micronfilms, using a stainless steel Gardner Knife. Evaporation at 100° C.under vacuum for 24 hours produced membranes of mean thickness 40microns.

The boiling water uptake of each membrane was determined as described inExample 4. The results are detailed in the Table below.

The procedure of Example 5 was followed, except that the membranes wereimmersed in refluxing acetone. The boiling water uptake of each membranewas determined as described in Example 4. The results are detailed inthe Table below.

Sulphonated Polymer Boiling Water Boiling Water from Polyether- Uptakebefore Uptake after Example 5d sulphone acetone acetone % w/w % w/wtreatment (%) treatment (%) 15 0 102 61 14.25 0.75 125 74 13.5 1.5 10567

Example 23

The procedure of Example 22 was followed except the sulphonated polymerfrom Example 1d was replaced with the polymer of Example 8d. The boilingwater uptake was determined as described in Example 4 and the procedureof Example 5 was followed, except that the membranes were immersed inrefluxing acetone. Results are provided in the table below.

Sulphonated Boiling Water Boiling Water Polymer Polyether- Uptake beforeUptake after from 8d sulphone acetone acetone (% w/w) (% w/w) treatment(%) treatment (%) 15 0 109 58 14.25 0.75 84 59 13.5 1.5 74 54 12.75 2.2569 48 12.0 3.0 49 39

The reader's attention is directed to all papers and documents which arefiled concurrently with or previous to this specification in connectionwith this application and which are open to public inspection with thisspecification, and the contents of all such papers and documents areincorporated herein by reference.

All of the features disclosed in this specification (including anyaccompanying claims, abstract and drawings), and/or all of the steps ofany method or process so disclosed, may be combined in any combination,except combinations where at least some of such features and/or stepsare mutually exclusive.

Each feature disclosed in this specification (including any accompanyingclaims, abstract and drawings), may be replaced by alternative featuresserving the same, equivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, each featuredisclosed is one example only of a generic series of equivalent orsimilar features.

The invention is not restricted to the details of the foregoingembodiment(s). The invention extend to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or to any novel one, orany novel combination, of the steps of any method or process sodisclosed.

1. A method of preparing an ion-conducting material, the methodcomprising: (i) selecting a first ion-conducting polymeric materialwhich has at least some crystallinity or which is crystallisable,wherein said first ion-conducting polymeric material includes a repeatunit which includes aromatic group containing moieties linked by —CO—and/or —Q— groups, wherein Q represents —O— or —S— provided that saidrepeat unit includes at least some ketone moieties; (ii) treating saidfirst ion-conducting polymeric material with a means to increase itscrystallinity, thereby to produce a treated ion-conducting polymericmaterial which is the same first ion-conducting polymeric material asthat selected in step (i), except that said material has increasedcrystallinity.
 2. A method according to claim 1, wherein the level ofcrystallinity in said treated ion-conducting material is at least 1%greater than the level of crystallinity in said first ion-conductingpolymeric material selected from step (i).
 3. A method according toclaim 2, wherein the level of crystallinity is at least 5% greater.
 4. Amethod according to claim 1, wherein said means to increase thecrystallinity of said first ion-containing polymeric material comprisesheating said first ion-conducting polymeric material when in asubstantially dry state.
 5. A method according to claim 1, wherein saidmeans to increase the crystallinity of said first ion-conductingpolymeric material comprises treatment of said first ion-conductingpolymeric material with a crystallinity increasing solvent.
 6. A methodaccording to claim 5, wherein said solvent is a polar aprotic solvent.7. A method according to claim 1, wherein the difference between thesensitivity of the material to water before and after treatment is atleast 5%.
 8. A method according to claim 1, wherein said firstion-conducting polymeric material has a moiety of formula

and/or a moiety of formula

and/or a moiety of formula

wherein at least some of the units I, II and/or III are functionalizedto provide ion-exchange sites; wherein the phenyl moieties in units I,II, and III are independently optionally substituted and optionallycross-linked; wherein said material is crystallisable or crystalline;and wherein m, r, s, t, v, w and z independently represent zero or apositive integer, E and E′ independently represent an oxygen or asulphur atom or a direct link, G represents an oxygen or sulphur atom, adirect link or a —O—Ph—O— moiety where Ph represents a phenyl group andAr is selected from one of the following moieties (i)* or (i) to (x)which is bonded via one or more of its phenyl moieties to adjacentmoieties


9. A method according to claim 1, wherein said first ion-conductingpolymeric material is sulphonated.
 10. A method according to claim 1,wherein said first ion-conducting polymeric material is a homopolymerhaving a repeat unit of general formula

or a homopolymer having a repeat unit of general formula

or a homopolymer having a repeat unit of general formula

or a homopolymer having a repeat unit of general formula

or a random or block copolymer of at least two different units of IV andV or of IV* and V*, wherein A, B, C, and D independently represent 0 or1, wherein m, r, s, t, v, w and z independently represent zero or apositive integer and E and E′ independently represent an oxygen or asulphur atom or a direct link, G represents an oxygen or sulphur atom, adirect link or a —O—Ph—O— moiety where Ph represents a phenyl group andAr is selected from one of the following moieties (i)* or (i) to (x)which is bonded via one or more of its phenyl moieties to adjacentmoieties


11. A method according to claim 1, wherein said first ion-conductingpolymeric material includes a multi-phenylene moiety and or a fused ringaromatic moiety which is functionalised to provide ion-exchange sites.12. A method according to claim 1, wherein said first ion-conductingpolymeric material includes a —O-biphenylene-O— or —O-naphthalene-O—moiety.
 13. A method according to claim 1, wherein said firstion-conducting polymeric material is a copolymer comprising a firstrepeat unit which is selected from the following: (a) a unit of formulaIV wherein E and E′ represent oxygen atoms, G represents a direct link,Ar represents a moiety of structure (iv), m and s represent zero, wrepresents 1 and A and B represent 1; (b) a unit of formula IV wherein Erepresents an oxygen atom, E′ represents a direct link, Ar represents amoiety of structure (i), m represents zero, A represents 1, B representszero; (c) a unit of formula V wherein E and E′ represent oxygen atoms, Grepresents a direct link, Ar represents a moiety of structure (iv), mand v represent zero, z represents 1 and C and D represent 1; (d) a unitof formula V wherein E represents an oxygen atom, E′ represents a directlink, Ar represents a moiety of structure (ii), m represents 0, Crepresents 1, D represents 0; or (e) a unit of formula V wherein E andE′ represents an oxygen atom, Ar represents a structure (i), mrepresents 0, C represents 1, Z represents 1, G represents a directlink, v represents 0 and D represents 1; (aa) a unit of formula IVwherein E represents an oxygen atom E′ represents a direct link, Arrepresents a structure (i)*, m represents 0, A represents 1, Brepresents 0; (bb) a unit of formula IV wherein E and E′ representoxygen atoms, Ar represents a structure (iv), m and w represent 0, Grepresents a direct link, s and r represent 1, A and B represent 1; (cc)a unit of formula IV wherein E and E′ represent oxygen atoms, Arrepresents a structure (i), m and w represent 0, G represents a directlink, s and r represent 1, A and B represent 1; and a second repeat unitwhich is selected from the following: (f) a unit of formula IV wherein Fand E′ represent oxygen atoms, G represents a direct link, Ar representsa moiety of structure (iv), m represents 1, w represents 1, s representszero, A and B represent 1; (g) a unit of formula IV wherein E representsan oxygen atom, E′ is a direct link, G represents a direct link, Ar (e)represents a moiety of structure (iv), m and s represent zero, wrepresent 1, A and B represent 1; (h) a unit of formula V wherein E andE′ represent oxygen atoms, G represents a direct link, Ar represents amoiety of structure (iv), m represents 1, z represents 1, v represents0, C and D represent 1; and (i) a unit of formula V wherein E representsan oxygen atom, E′ represents a direct link, G represents a direct link,Ar represents a moiety of structure (iv), m and v represent zero, zrepresents 1, C and D represent 1; (j) a unit of formula IV wherein Eand E′ represent oxygen atoms, G represents a direct link, Ar representsa moiety of structure (v), m represents 0, w represents 1, s represents0, A and B represent 1; (k) a unit of formula V wherein E and E′represent oxygen atoms, G represents a direct link, Ar represents amoiety of structure (v), m represents 0, z represents 1, v represents 0,C and D represent
 1. 14. A method according to claim 1, the methodincluding preparing a precursor membrane which includes said firstion-conducting polymeric material and, subsequently, treating saidprecursor membrane with said means to increase its crystallinity.
 15. Amethod according to claim 1 which includes a step of associating acatalyst material with said ion-conducting material.
 16. Anion-conducting material prepared in a method according to claim
 1. 17. Amethod of preparing a Membrane Electrode Assembly (MEA) which includesassociating catalyst material and/or an electrode with an ion-conductingmembrane prepared in a method according to claim 1.